The present invention relates generally to the field of flow control valves and the construction thereof. More specifically, the present invention relates to the internal components of flow control valves including the elastomer sleeve that provides a sealing surface for the valve components and connections.
Flow control valves such as, for example, knife gate valves or line blind valves, are used to control the flow of fluids and can be particularly well suited for use with abrasive and corrosive slurries such as are encountered in, for example, the mining, pulp or paper industries. One form of gate valve known in the art includes a housing constructed of two halves that when coupled together form the valve housing and passageway therethrough. On opposite sides of the housing are connections for installing the valve in a pipe line, for example, the housing can be bolted to a flange end of a pipe. To control the flow of fluid through the valve, the valve includes a gate that, in operation, translates or travels between the two valve halves. Each valve half defines a sleeve recess in which is disposed a valve sleeve. The valve sleeves are axially aligned to define the passageway and provide a sealing function in the valve. To seat the valve sleeves in the recesses, the sleeves can be configured with ridges or lips to conform to the contours of the sleeve recess. The two valve sleeves seal against one another when the gate is in the open configuration to allow for fluid flow through the valve while substantially preventing fluid leakage from the valve housing. When the gate is in the closed position, the opposing sleeves seal against the gate and substantially prevent the fluid that collects against the gate from leaking from the housing. One exemplary valve housing and sleeve assembly includes the CLARKSON KGD WAFER STYLE SLURRY KNIFE GATE VALVE from TYCO FLOW CONTROL as shown in the TYCO FLOW CONTROL data sheet entitled “Clarkson KGD Wafer Style Slurry Knife Gate Valve 2” thru 24” (2005). Other known valves and valve sleeves are shown and described in, for example, U.S. Pat. Nos. 4,895,181 and 5,730,149.
Valve sleeves not only create a sealing surface between the valve gate and one another, but the valve sleeves also provide a support surface to engage the flange surfaces of the valve housing or other piping elements coupled to the valve housing. Known valve sleeves use a two-piece construction in which the sleeve has a seat portion that is disposed within the sleeve recess of the valve housing and a separate support disc which snaps to the seat portion to form a flange for engagement with the flange face of the housing. The separate support disc is generally sized to the pipe to which the valve housing is coupled. In addition, the support disc is generally made of a harder plastic or other hard material to provide a surface against which the adjoining pipe may rub. Moreover, the material forming the support disc is dissimilar to the material of the seat portion of the sleeve.
Because the support disc is made of a hard material, its ability to provide a tight seal between flange surfaces, in some operative conditions, may be limited. Moreover, because the support discs are constructed from a material different than the valve seat portion, the flange and its support disc may not be as chemically resistant as the seat portion. Accordingly, the flange and its support disc may be susceptible to long term fatigue, such as cracking or breaking. In addition, due to the inelasticity of the hardened support disc, the support disc may not withstand or be resilient to over-compression by the flange bolts coupling the valve into the piping assembly. Alternative known sleeve designs include an integrated support disc portion. However, these alternative designs do not effectively address the issue of over-compression at the flange bolts.